Regional anesthesia
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Regional anesthesia · Sep 1995
Randomized Controlled Trial Clinical TrialHyperosmolarity does not contribute to transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine.
In addition to major neurologic injury, local anesthesia toxicity may also include less severe but more common neurologic side effects. The authors recently observed symptoms suggestive of transient radicular irritation in one third of patients after spinal anesthesia with hyperbaric 5% lidocaine, whereas evidence of neurologic symptoms was lacking with hyperbaric 0.5% bupivacaine. The purpose of this prospective double-blinded study was to evaluate if the high osmolarity of hyperbaric 5% lidocaine solution might contribute to the development of transient radicular irritation. ⋯ The results suggest that transient radicular irritation did not result from the marked hyperosmolarity of the hyperbaric 5% lidocaine. However, because lidocaine and bupivacaine were not administered at equipotent dosages, the relative potential for both drugs to induce transient radicular irritation remains to be determined.
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Regional anesthesia · Sep 1995
Randomized Controlled Trial Clinical TrialAlkalinization of local anesthetics. Which block, which local anesthetic?
A number of clinical studies have been performed in an attempt to establish the effects of alkalinization on potency of local anesthetics. Conflicting results were obtained probably because different studies used different methods as well as different definitions of the effects. To determine the efficacy of alkalinization using different local anesthetic solutions and different regional blocks, 180 patients were studied in a randomized, double-blind fashion. The local anesthetic solutions studied were bupivacaine, mepivacaine, and lidocaine; the regional blocks studied were epidural block, axillary brachial plexus block, and femoral and sciatic nerve block. ⋯ Alkalinization produced the best results with lidocaine and bupivacaine for epidural block, with lidocaine for brachial plexus block, and with mepivacaine for sciatic and femoral nerve blocks.
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Regional anesthesia · Sep 1995
Randomized Controlled Trial Comparative Study Clinical TrialThoracic versus lumbar administration of fentanyl using patient-controlled epidural after thoracotomy.
Epidural fentanyl injection can provide analgesia following thoracotomy, but where to insert the catheter is a matter of debate. The study compares the effects of thoracic and lumbar patient-controlled epidural fentanyl on analgesia, fentanyl requirements, and plasma levels after thoracotomy. ⋯ The authors concluded that there is little if any advantage of thoracic over lumbar patient-controlled epidural fentanyl administration in patients after thoracotomy with respect to analgesia, fentanyl requirements, and plasma levels.
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Regional anesthesia · Sep 1995
Randomized Controlled Trial Clinical TrialEpinephrine prolongs duration of subcutaneous infiltration of local anesthesia in a dose-related manner. Correlation with magnitude of vasoconstriction.
Epinephrine is frequently combined with local anesthesia to prolong analgesia. Determination of the minimal concentration and the dose of epinephrine that produces prolongation of analgesia is important in the face of epinephrine's potential for systemic and local toxicity. The authors undertook this study to determine a dose-response curve of epinephrine on duration of analgesia of both 1% lidocaine and 0.25% bupivacaine after local infiltration. In order to determine whether epinephrine-induced vasoconstriction affected duration of analgesia, the authors correlated duration of analgesia with magnitude of local vasoconstriction as measured with laser Doppler flowmetry. ⋯ Epinephrine prolongs duration of analgesia after local infiltration in a dose-related manner. Addition of epinephrine in concentrations of 1:50,000 or 1:200,000 increases duration of analgesia after local infiltration by approximately 200%. Addition of doses as dilute as 1:3,200,000 still increases duration of analgesia by approximately 100%. Duration of analgesia appears to correlate with magnitude of epinephrine-induced vasoconstriction using laser Doppler flowmetry. Based on study data, the use of epinephrine in concentrations from 1:200,000 to 1:3,200,000 is recommended for prolongation of analgesia after local infiltration.
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Regional anesthesia · Sep 1995
Comparative StudyChronic subarachnoid midazolam (Dormicum) in the rat. Morphologic evidence of spinal cord neurotoxicity.
In humans, the benzodiazepine midazolam has been reported to exert an antinociceptive action after subarachnoid injections. It has been shown that subarachnoid midazolam given to rabbits produces significant pathology in spinal cord morphology, as detected with light microscopy. In order to further characterize these changes, this study was performed, using a more sensitive histologic technique, including electron microscopy as well as unbiased morphometry. ⋯ The authors found that chronic subarachnoid administration of midazolam gives objective signs of neurotoxicity in the rat spinal cord. The authors' findings are in contrast to those of an earlier light microscopic study in the rat. The present results emphasize both the necessity of morphometric and ultrastructural studies before spinal administration of novel drugs to humans and the neurotoxic potential of midazolam. Since neurotoxicity of midazolam now has been demonstrated in both rats and rabbits, there may be reason to be sceptical of the use of subarachnoid midazolam in humans.